Modular multilevel converter (MMC) is a new type of voltage transforming circuit. Being capable of realizing electrical energy transformation for middle/high voltages with features such as little harmonic in output and high degree of modularity, the MMC has wide application prospect in the electrical power system.
In prior art, the MMC forms a current path via multiple power modules connected in series, and input voltages can be a higher voltage for that the multiple power modules are connected in series, allowing the MMC to transfer energy from one high level to another voltage level. However, due to the material and complex interface of optical fibers, which are typically adopted as the signal transmission carrier between the master controller and the power modules in the middle/high voltage system, it is difficult for the MMC to detach and introduce individual power module without cutting off the electricity.